Many devices are known for dispensing molten thermoplastic materials from blocks of solid thermoplastic material pressed into the device by the thumb of the user's hand, such as the prior art devices described in U.S. Pat. Nos. 3,204,828 and 3,298,572.
Generally, such devices comprise a barrel member having an internal melting chamber which communicates with an outlet opening through a nozzle, and a sleeve with a through opening having one end secured to the barrel member with its through opening communicating with the end of the melting chamber opposite the nozzle. The sleeve is adapted to receive an elongate cylindrical block of solid thermoplastic material which fits closely within the through opening in the sleeve, with one end portion of the block in the melting chamber and the other end portion projecting through the sleeve. Means are provided for heating the barrel member to melt the end portion of the block therein, and the device includes a handle positioned so that an operator can grip the handle with the fingers of one hand while pressing the block through the sleeve and into the melting chamber with the thumb of that hand to force molten thermoplastic material out of the melting chamber through the nozzle.
While such devices function effectively and provide great versatility in regulating the amount of thermoplastic material flowing through the devices, a problem can occur after the operator places a second block of thermoplastic material end to end with the block in the sleeve and presses on the outer end of the second block. The operator must hold the second block in place, thus occupying the operator's second hand which may be needed elsewhere such as to manipulate articles to which the molten thermoplastic material is being applied. If the operator does not hold the second block in place and releases the pressure on the second block as must be done to stop the flow of the molten thermoplastic material, or applies pressure in some direction other than axially along the second block before its leading end enters the sleeve, the second block can fall or fly away from the block already in the sleeve, which is inconvenient, distracting, and wasteful of the operator's time.
A device for dispensing molten thermoplastic material described in my U.S. Pat. No. 4,552,287, and incorporated herein by reference, provides, among other things, means for holding and properly positioning a second block of solid thermoplastic material at the end of a block of that material already in a sleeve and a melting barrel of a device of the type described above, even before the second block enters the outer end of the sleeve, thereby freeing the use of the operator's second hand for other activities.
That device, however, will hold a maximum of less than three block of thermoplastic material, and thus frequent loading of the device is required if the device is used continuously.
My U.S. patent application Ser. No. 570,245, describes a magazine assembly for use with the device described in my U.S. Pat. No. 4,552,287. The magazine assembly provides means for holding and properly positioning a lowermost block of thermoplastic material in aligned end-to-end relationship with a block of thermoplastic material within the sleeve while affording use of the operator's thumb to press the lowermost block through the sleeve and into the melting chamber and holding a stack of blocks of thermoplastic material normally above the lowermost block. The stack of blocks can be caused to drop down to position the next lowermost block in alignment with the remainder of a block of thermoplastic material that has been pressed through the sleeve by reciprocal movement of a thumb operated slide which provides both a pusher for the lowermost block and a support for the stack of blocks above the lowermost blocks. While this magazine assembly can be easily operated and holds a relatively large amount of thermoplastic material, it is more bulky than may be desired and must be loaded with a plurality of relatively small thermoplastic blocks.